In view of the increasing costs of operating motor driven vehicles and more particularly, the increasing fuel costs for running these vehicles, many fuel conservation programs have been initiated. One of the main ways to conserve on fuel consumption, as well as wear and tear on the vehicle, is to limit the rate of both acceleration and deceleration. To date, a number of acceleration warning systems have been devised. However, improvements can be made to these systems.
One design of an acceleration warning system is shown and described in U.S. Pat. No. 4,171,030 issued Oct. 16, 1979 to Hermann Ruhl. The system in this U.S. Patent is one in which a control or warning device is activated by undesirably high rates of vehicle acceleration, either in the positive or the negative sense, i.e. acceleration or deceleration. However, one of the drawbacks of this patented system as well as other presently available systems is that they are set to operate at a fixed acceleration rate regardless of the vehicle's speed and do not take into account, that certain rates of acceleration may be desirable at one speed while being undesirable at a different speed.
Observations of the acceleration patterns in traffic show that vehicles tend to accelerate relatively fast at low driving speeds and much more slowly at higher driving speeds. Generally speaking, the acceleration rate decreases with increasing driving speed, which is fully understandable in view of the fact that at low speeds, a relatively high acceleration can be achieved with a relatively lower engine power than is required at higher speeds. Therefore, the higher the driving speed, the more power required to keep the vehicle moving at a steady speed, so that less power is available for additional acceleration. Additionally, it is possible to accelerate at a faster rate at low speeds with a relatively low fuel consumption since less power is required to accelerate at low speeds than at higher speeds. This means that higher accelerations at lower driving speeds are not as fuel consuming as accelerations at higher driving speeds. Furthermore, with increasing driving speeds the driver becomes more aware of a higher noise level from the moving vehicle and from the engine, indicating to the driver that higher power is required to accelerate the vehicle at these higher speeds. The fact that more power is required for acceleration at higher speeds, is also indicated by the accelerator pedal position which must be depressed considerably farther than is required at lower driving speeds.
Acceleration warning systems as described in U.S. Pat. No. 4,171,030 which are limited in that they react to a fixed acceleration rate regardless of speed, will not meet the actual conditions of traffic and therefore, do not reflect the patterns of acceleration in speed selection which would be chosen by an experienced well-trained driver. These limited warning device systems do not permit control of the vehicle in a manner corresponding to the natural pattern of acceleration rates which are acceptable and found in general traffic patterns.
It would not be feasible to provide an acceleration warning system with a rate of acceleration control set to operate at a medium acceleration rate between slow and high speeds. Such a setting would have the effect that at slower driving speeds, the desirable acceleration rate could still not be achieved because the warning would occur at a rate something below that accepted at slow speeds, while at higher speeds over accelerating would be permitted before the warning could be activated.
The present invention provides an acceleration monitoring system which operates more efficiently than any of the systems described above. The system of the present invention which can be used as a warning and/or control system, is adapted to react to different acceleration rates at different speeds traveled by the vehicle. More particularly, the acceleration monitoring system for motor driven vehicles of the present invention has, in combination, speed measuring means providing an output signal proportionate to and changing with the speed of the vehicle, acceleration measuring means providing an output signal corresponding to the output signal from the speed measuring means, acceleration warning switch means having a variable switch point for switching at different predetermined rates of acceleration, speed sensing means controlling the switch means and changing the switch point according to the predetermined rates of acceleration in relation to speed, and monitoring means in the form of a control or warning device activated by the switch means which is responsive to the output signal from the acceleration measuring means.
It will be understood from the description above, that the acceleration monitoring system of the present invention is one which is adapted to meet every day driving demands for natural traffic flows.